a combining form occurring in loanwords from Greek and Latin, where it meant “eight” (octagon; octastyle), on this model, used in the formation of compound words, and in chemical terms specialized to mean “having eight atoms” (octavalent).
English Affixes From A To Z: A One-Stop List Of Suffixes, Prefixes, and Combining FormsIn English, we love to make new words by adding all sorts of bits to the front and back of existing terms. These are called affixes, and they are added to the base or stem of a word. When attached to the end of word, the affix is called a suffix. And to the beginning? A prefix.
Origin of octa-
< Greek okta-, combining form of oktṓ eight
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for octa-
a variant of octo-
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012